This invention relates to a bumper for a vehicle, comprising a hat beam adapted to have its crown directed towards the vehicle body, a cover attached to the side flanges of the hat beam and having a longitudinal recess that extends into the hat beam to a depth of between {fraction (1/10)} and ⅓ of the profile height of the hat beam, and an energy absorbing foamed body that fills out the recess and extends out of the recess so that 65-85% of the depth of the foamed body is outside the hat beam. A closed cross-section beam having a longitudinal recess may be employed instead of a hat beam.
A bumper of this kind is known from WO 9920490. The foamed body is used to absorb energy by being compressed before the hat beam will be deformed to take up energy. The foamed body extends over the side flanges of the hat beam and the front surface of the foamed body is almost flat so that, if the bumper hits a barrier, the foam will be compressed to compactness on the side flanges and will become totally stiff while the foam therebetween will still be resilient. The foam in the middle cannot be compacted to stiffness until the beam itself has been deformed. In the above mentioned publication, a modified bumper is also shown which has a flat cover and the foam will therefore give a more uniform resistance force when compressed.
It is an object of the invention to provide a bumper beam with a foamed body that gives a more uniform load vertically on an object that is hit, for example the legs of a pedestrian, combined with a reduced horizontal extension of the entire bumper for a given strength. To this end, the part of the foamed body that extends out of the beam, which can be a hat beam or a closed cross-section beam, has either at most the same area as in the recess or alternatively it widens out over the side flanges and has recesses that reduce the difference in compactness to be less than 15% when the bumper hits a vertical pillar and any part of the foamed body is compresses to total compactness.